Leg (feet) is already a unit of distance.

British of all people would know. After all they meet Gandhi

Charge what you think is right if this not your main business. Those who charge higher do it for living.

Btw, i’m not into teaching (except when teaching my yr 8 son getting him ready for gcse)

As a student 25 yrs back, I rarely had ‘penny drop’ moments. Only thing which came close was when doing A level equivalent my teacher told us that all units in physics could be derived same as algebraic equations and don’t have to be remembered.

Breaking down the equation in smaller parts.
Or use smaller equations to begin with.